Gamma camera systems are used in nuclear medicine to produce an image based on the internal physiology of a patient. In the process of examination, a radio-pharmaceutical is introduced into the patient. The substance migrates to certain organs of the patients body. Measuring radiation emitted from the patient can be used to image the distribution of the radio-pharmaceutical in the patient. PCT Publication WO 98/27443, the disclosure of which is incorporated herein by reference, describes a light weight gamma camera and details relating to performing such measurements.
In order to supply a tomographic image of a patient, it is common practice to measure the radiation with a machine controlled gamma camera performing a contour trajectory of the patient. Such a process requires moving the gamma camera with precise positioning around the patient in order to construct an accurate tomographic image. U.S. Pat. No. 4,649,277 to Terra et al., the disclosure of which is incorporated herein by reference, describes a gamma camera mounted on a gantry supported by a column running on guides. By positioning the patient in a selected position and rotating the gamma camera around the axis of the patient, a tomographic image is formed.
In order to improve sensitivity and speed up the process of forming a tomographic image it has been suggested using two cameras rotating about the axis of the patient. U.S. Pat. No. 5,594,251 to Fleury et al., the disclosure of which is incorporated herein by reference, describes a system with a fixed base and two gamma cameras rotating about a barycentric axis.
In U.S. Pat. No. 5,811,813 to Maor, the disclosure of which is incorporated herein by reference, there is described a gamma camera head with two detectors forming an angle between them. A dual detector gamma camera head allows quicker and more accurate measurements by sensing radiation at two angles at the same time. This is useful for spot measurements using a non moving camera. Additionally, in tomographic images a dual detector head enables measuring a larger arc with less rotation, for example a 180° arc with a 90° rotation.